As a tour guide on the idyllic island of Boa Vista in Cape Verde, Safiro Furtado led a mostly European clientele on jaunts along silky sand dunes, whispering palm trees, and world-class beaches, his family said. He arrived in Dorchester five months ago to reconnect with his mother and sister, whom he had not seen in a decade.

Daniel Abreu grew up in Cape Verde, worked as a police officer there, and arrived in Dorchester four years ago, his relatives said. Abreu, 29, and Furtado, 28, became friends and worked together for a cleaning company based on Hamilton Street in Dorchester.

Both men were fatally shot early Monday, after leaving an undisclosed bar in downtown Boston, according to their families.

Police say a gray or silver sport utility vehicle with Rhode Island license plates pulled alongside the BMW sedan Abreu was driving just after 2 a.m. and fired numerous times into the car. Abreu had stopped at a traffic light on Shawmut Avenue, on the Interstate 90 overpass, and was apparently about to make a left turn onto Herald Street.

Furtado was in the passenger seat, and three other friends were in the back seat, authorities said. One back-seat passenger was shot three times in the arm, but survived. He was rushed to Tufts Medical Center and was treated and released. The other two occupants were unharmed. They ran from the scene, but were later in contact with authorities, police said.

No arrests have been made, and authorities have not located the SUV tied to the shooting by eyewitness accounts, said Cheryl Fiandaca, spokeswoman for the Boston Police Department.

Late Tuesday, police released the names of the victims. A law enforcement official said Monday that the shooting may have been gang-related. On Tuesday, however, other officials said the victims did not have criminal records and were not involved in gangs. The motive remained unclear.

‘This is a mystery, why anyone would want to kill two people who never bothered anyone.’

Abreu’s and Furtado’s relatives said neither men had ties to gangs. They remembered the two as fun-loving and hard workers who spent most of their off-time at home with family or playing soccer at a local field.

“My son, he was a good boy; he never hurt anyone, so why did this happen to him?” wailed Maria Teixeira, 58, Furtado’s mother, speaking in Cape Verdean Creole as she sat at her kitchen table in Dorchester, relatives and family friends standing nearby.

“I just want to find out who did this and for there to be justice,” she said. “I’m hopeless, I’m full of despair. I couldn’t believe this happened, and I still don’t believe it.”

Furtado often sat on the stairs leading to the first-floor entrance of the Hamilton Street three-decker, where he lived with his mother and sister. The girlfriend of the unidentified man wounded in the shooting said Furtado had become something of a fixture in the neighborhood in only five months.

“I know it will be weird when I step outside and not see Safiro on those steps,” she said. She declined to give her name, saying her boyfriend was a victim of a violent crime.

Abreu and Furtado worked for Jose Centeio’s company, Advanced Detail Cleaning Service. Abreu also worked, mostly nights, at the South Shore YMCA in Quincy.

Centeio said he and Furtado are cousins, and Abreu is related to Centeio’s wife.

“They were my employees, but they were also very good friends of mine, like brothers,’’ Centeio said.

“This is a mystery, why anyone would want to kill two people who never bothered anyone,” he said. “They had no issues with anyone, and I’m sure of that, because I spent a lot of time with them.”

Brian Ballou can be reached at bballou@globe.com. Follow him on Twitter @GlobeBallou.

BostonGlobe.com complimentary digital access has been provided to you, without a subscription, for free starting today and ending in 14 days. After the free trial period, your free BostonGlobe.com digital access will stop immediately unless you sign up for BostonGlobe.com digital subscription. Current print and digital subscribers are not eligible for the free trial.

Thanks & Welcome to Globe.com

You now have unlimited access for the next two weeks.

BostonGlobe.com complimentary digital access has been provided to you, without a subscription, for free starting today and ending in 14 days. After the free trial period, your free BostonGlobe.com digital access will stop immediately unless you sign up for BostonGlobe.com digital subscription. Current print and digital subscribers are not eligible for the free trial.